OF NDFC

OF NDFC

[Valentine Barshak]

Is anybody working on the device-tree-aware ppc 44x NAND flash controller (ndfc)  driver?

Thanks,
Valentine.

Re: OF NDFC

[Josh Boyer]

On Wed, 5 Sep 2007 22:17:03 +0400
Valentine Barshak <vbarshak@ru.mvista.com> wrote:

> Is anybody working on the device-tree-aware ppc 44x NAND flash controller (ndfc)  driver?

Not to my knowledge.  We sort of need a decent binding for NAND flash
in general first.  And David's recent flash binding doesn't address
NAND flash.

It's on my list of things to do, but if someone gets there first then
great.

josh

Re: OF NDFC

[Segher Boessenkool]

>> Is anybody working on the device-tree-aware ppc 44x NAND flash 
>> controller (ndfc)  driver?
>
> Not to my knowledge.  We sort of need a decent binding for NAND flash
> in general first.

Not really.  You can put the NAND controller in the device
tree without describing the NAND flash itself -- and for that,
you only need a "name", "compatible", "reg", and maybe some
interrupt stuff.


Segher

Re: OF NDFC

[Josh Boyer]

On Thu, 6 Sep 2007 15:06:03 +0200
Segher Boessenkool <segher@kernel.crashing.org> wrote:

> >> Is anybody working on the device-tree-aware ppc 44x NAND flash 
> >> controller (ndfc)  driver?
> >
> > Not to my knowledge.  We sort of need a decent binding for NAND flash
> > in general first.
> 
> Not really.  You can put the NAND controller in the device
> tree without describing the NAND flash itself -- and for that,
> you only need a "name", "compatible", "reg", and maybe some
> interrupt stuff.

He said driver.  To test a driver, you'd need the binding for both the
controller, and the NAND flash it controls.  Otherwise, the driver
isn't going to do much :).

josh

Re: OF NDFC

[Valentine Barshak]

Josh Boyer wrote:
> On Thu, 6 Sep 2007 15:06:03 +0200
> Segher Boessenkool <segher@kernel.crashing.org> wrote:
> 
>>>> Is anybody working on the device-tree-aware ppc 44x NAND flash 
>>>> controller (ndfc)  driver?
>>> Not to my knowledge.  We sort of need a decent binding for NAND flash
>>> in general first.
>> Not really.  You can put the NAND controller in the device
>> tree without describing the NAND flash itself -- and for that,
>> you only need a "name", "compatible", "reg", and maybe some
>> interrupt stuff.
> 
> He said driver.  To test a driver, you'd need the binding for both the
> controller, and the NAND flash it controls.  Otherwise, the driver
> isn't going to do much :).
> 
> josh
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev
AFAIK, NAND flash is autodetected by reading it's ID at runtime, so 
there should be no need for flash bindings.
Thanks,
Valentine.

Re: OF NDFC

[Josh Boyer]

On Thu, 06 Sep 2007 17:30:08 +0400
Valentine Barshak <vbarshak@ru.mvista.com> wrote:

> AFAIK, NAND flash is autodetected by reading it's ID at runtime, so 
> there should be no need for flash bindings.

Well, I'm not really sure.  CFI and JEDEC can both be probed as well,
and we're working on a binding there.  But if you think you can come up
with a driver for NDFC that doesn't require some kind of device tree
description of the devices it controls, then by all means go for it.

josh

Re: OF NDFC

[Segher Boessenkool]

>> AFAIK, NAND flash is autodetected by reading it's ID at runtime, so
>> there should be no need for flash bindings.
>
> Well, I'm not really sure.  CFI and JEDEC can both be probed as well,
> and we're working on a binding there.

JEDEC cannot be reliably probed.  CFI can be _almost_ probed,
you need to know the interleaving though, to handle some edge
cases.  Oh, and you need to know it _is_ CFI, of course.

> But if you think you can come up
> with a driver for NDFC that doesn't require some kind of device tree
> description of the devices it controls, then by all means go for it.

I don't know whether NAND can be reliably probed; most "standard"
NAND devices can be, but I don't know what standards are involved
here, if any.  We'll need some MTD people help here.

OTOH, it definitely is better to describe only the NAND controller
and not the devices, than to put nothing at all in the device tree.
We had this same situation with NOR flash before, already...


Segher